The invention relates to a safety belt apparatus for motor vehicles comprising a safety belt and a belt tensioner.
Belt tensioners ensure that in the event of an accident the safety belt contacts the body of the respective occupant tightly and that the protective effect of the safety belt is optimized.
According to the present invention, a safety belt apparatus that accomplishes a reliable tensioning of the safety belt is provided. In particular, the apparatus provides a tensioning as independent as possible of other means of the safety belt apparatus.
The apparatus may include a belt tensioner attachable to the vehicle in the region of a free belt section. The belt tensioner cooperates with the safety belt in the region of the free belt section to alter the effective length of the safety belt. Since the belt tensioner is attachable in the region of a free belt section and cooperates with the safety belt in the region of this free belt section, the belt tensioning can take place independently of other means of the safety belt apparatus. The non-dependence on other parts of the apparatus offers the advantage that the belt tensioner can be subsequently integrated in existing safety belt apparatuses and can be made available as a retrofitting kit. The effective length of the safety belt at the occupant vehicle can be altered independently of a belt tensioner.
A further advantage of the present invention is that the effective length of the safety belt, that is the section of the safety belt between the belt tensioner and the buckle which restrains the vehicle occupant in the event of an accident, is not only reduced, but can also be extended in a defined manner. The contact pressure of the safety belt on the occupant of the vehicle can thus be set directly. A control device can be provided for adjusting the effective length of the safety belt. The length can be set in the normal operation of the vehicle in accordance with a pre-set contact pressure, which can, for example, be selected by the vehicle occupant himself. Appropriate measuring devices can be provided to measure a value corresponding to the contact pressure, e.g. the belt tension or a force applied to a further component via the belt in order to provide safety belt apparatus with a xe2x80x9ccomfort function.xe2x80x9d
Moreover, the present invention provides an optimum protection against a so-called xe2x80x9csecond impactxe2x80x9d, in which the vehicle is exposed to a second impact subsequent to a first impact. Such a second impact occurs, for example, when the vehicle drives through an obstacle (first impact) and is brought to a halt in a subsequent second impact. The belt tensioner can furthermore be deliberately used, independently of other means of the safety belt apparatus, for the purpose of positioning the vehicle occupant prior to the second impact such that the safety belt can again develop its optimum protective effect. Moreover, the belt tensioning in accordance with the present invention can be designed such that existing occupant restraining systems of the vehicle are reinforced or complemented in their protective effect, in particular, with respect to the second impact protection.
Another embodiment of the present invention includes a belt tensioner comprising a clamping unit which is steerable starting from a rest position into clamping engagement with the safety belt. The cooperation between the belt tensioner and the safety belt is effected by clamping of the respective belt section so that the clamped belt section can be moved to alter the effective length of the safety belt in the desired manner, i.e. the safety belt contacts the body of the vehicle occupant in a more or less tight manner.
In a further embodiment of the present invention, the path of the safety belt is altered by the belt tensioner. The path of the safety belt, and thus the effective length of the safety belt, can be directly set, for example, by forming a loop in the belt which can be changed in size.
In accordance with a further preferred embodiment, the belt tensioner can be moved along the belt section. Substantially linear movement of the belt tensioner can be utilized in order to steer a clamping unit of the belt tensioner into clamping engagement with the safety belt. The non-dependence of the apparatus in accordance with the invention on other vehicle means is realized by the belt tensioner utilizing its own movability.
In a further embodiment of the invention, the belt tensioner includes a control unit which can be driven directly to make a movement along the belt section and via which the clamping unit can be steered into clamping engagement with the safety belt. Preferably the clamping unit can be moved together with the control unit, with a lag with respect thereto, along the belt section. The clamping unit can be coupled to the control unit such that the lag of the clamping unit is the result of inertia. The lag is utilized to steer the clamping unit into clamping engagement with the safety belt. After activation of the belt tensioner drive, the control unit is set in motion and this motion is converted into the clamping movement of the clamping unit. The clamping unit is thereby brought into clamping engagement with the safety belt. The clamping unit and the clamped safety belt are subsequently moved together with the control unit, whereby the desired belt tensioning is achieved.
The clamping unit can comprise at least one clamping member which is provided with a control surface at its side remote from the safety belt which can be acted upon by a control section of the control unit. Preferably, the clamping member is formed as a clamping wedge and the control section as a correspondingly shaped cooperating wedge.
The clamping unit preferably comprises at least two oppositely disposed clamping members which can be moved toward one another by movement of the belt tensioner. The clamping members serve as clamping jaws between which the safety belt can be clamped. The clamping members can be formed as identically designed clamping wedges which are arranged symmetrically with respect to the safety belt and which are each provided at their side remote from the safety belt with an oblique surface extending at an angle with respect to the direction of movement of the control unit.
Alternatively, the belt tensioner can comprise at least two clamping reels which can be moved relative to one another in order to form a clamping gap for the safety belt, with at least one clamping reel being provided with a rotary drive.
To alter the effective length of the safety belt, the safety belt is first clamped between the two clamping reels, which can be moved accordingly for this purpose, with the clamping reel provided with the rotary drive being subsequently set into rotation in order to transport the safety belt through the clamping gap. The direction, the degree and the speed of the alteration in length can be deliberately set with high precision.
In accordance with a further embodiment of the present invention, the belt tensioner can comprise at least two guide reels around which the safety belt is guided and which can be moved relative to one another to alter the path of the safety belt in order to adjust the effective length of the safety belt by altering its path.
The path of the safety belt guided round the guide reels and guided in a compulsory manner and may be pre-set in any relative position of the guide reels.
The belt tensioner is preferably located along a free belt section of the safety belt. In the free belt section, the belt is not constrained or in contact with other parts such as, for example, winding reels, anchors, buckles and guides. The free belt section having the belt tensioner may be located between a belt winding reel and a belt deflector or a guide device for the belt. In a safety belt apparatus in which no belt deflector and no belt guide is provided, the belt tensioner is preferably arranged in the free belt section located between a belt winding reel and the level of the shoulder of the respective occupant.
It is particularly preferred if the belt tensioner is mounted in the region of the B or C pillar of the vehicle, in particular within the B or C pillar. Alternatively, it is also possible to arrange the belt tensioner in the region of the rear shelf, in particular beneath the rear shelf of the vehicle.
Preferably, the present invention provided a belt tensioner that can be moved out of a rest position against the restoring force of a restoring means, in particular of a return spring. For example, a clamping of the safety belt or a previously set path of the safety belt corresponding to a certain effective length of the safety belt can be cancelled or altered again in a simple manner. A reversible system is thereby created.
The belt tensioner preferably comprises a separate drive, in particular, in the form of an electric motor.
The belt tensioner can be designed to ideally achieve the protective function intended for it independently of other means of the vehicle.
The present invention relates to a belt tensioner for motor vehicles which can be mounted to the vehicle in the region of a free belt section and which cooperates with the safety belt in the region of the free belt section in order to alter the effective length of the safety belt. The belt tensioner may be formed as a retrofitting kit which can be subsequently integrated in a safety belt apparatus of the vehicle. The belt tensioner can be designed such that the structure of the vehicle is used.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only, and not restrictive of the invention as claimed.